Equalizing pressure bandage



United States Patent Donald Patience Barrington, Illinois; Herbert Knohl Seneca, South Carolina 747,525

July 25, 1968 Aug. 1 l, 1970 The Kendall Company Walpole, Massachusetts a Corp. of Massachusetts [72] Inventors Appl. No. Filed Patented Assignee EQUALIZING PRESSURE BANDAGE 11 Claims, 7 Drawing Figs.

U.S. Cl

128/169, 128/156 Int. Cl A6lf 13/00 Primary Examiner- Adele M. Eager Anorney- James I. Fawcett ABSTRACT: A woven ribbon-like, light weight, low-modulus compression bandage with ravel resistant side edges incorporating elastomeric warp yarns, synthetic crimp stretch warp yarns and spun warp yarns having the capacity when used as a wrap under tension of partially relaxing after application thereby reducing the initial compression caused by the retroactive force of the bandage.

ii 12 11 f2 1! 12 11 12' III EQUALIZING PRESSURE BANDAGE BACKGROUND OF THE INVENTION This invention is concerned with woven low-modulus compression bandages containing elastomeric warp yarns.

For some purposes non-elastic bandages are unsuitable since if used as compression bandages they must be quite tightly wrapped and if wrapped over a swelling body joint or the like soon become so painfully tight that they must be loosened. For compression type bandaging, therefore, an elastic bandage is generally preferred. Those which have been available prior to this invention have been of the heavy type and have had relatively high modulus whether the stretch be due to the use of elastic warp yarns or to the use of high twist cotton yarns. These bandages are effective when applied by an experienced person such as an athletic trainer, but when applied by those with limited experience have been unsatisfactory since they are generally applied either so loosely that the bandage will not stay in place or so tightly that they too must be loosened particularly if applied to a swelling joint.

In some foreign countries, among which Japan is prominent, light weight cotton bandages for wrapping dressed wounds containing some elastomeric warp yarns have been available. The initial modulus of these bandages when stretched 100 percent is ofthe order of.22 pound per inch width. These characteristics may be satisfactory for retaining wound dressings in place and providing absorption even when the compressive force exerted by the bandage decays within a short time to .16 pound per inch width, but they do not make a satisfactory compression bandage for controlling excessive swelling. If such a bandage is wrapped at low or medium tension it is not much different than a non-elastic bandage. When the elastomeric warp yarns are under high tension the bandage compression is too high and the elastomeric relaxation is insufficient to relieve this high compression especially where swelling is involved.

SUMMARY OF THE lNVENTlON One object of this invention is to provide a ribbon-like elastic bandage which can be applied by a personuntrained in such application over a wide range of wrapping elongation with a wide range of applied force without rendering the bandage non-functional and unduly restrictive.

Another object of the invention is the provision of a bandage which will relax its compressive force after application but remain in place and exert compressive force within the effective range for an acceptable compressive bandage.

Another object is to provide an elastic compressive bandage which because of its construction is inexpensive to manufacture and is cool and light when worn.

These and other objects of the invention will be apparent from an examination of the drawings and their description and of other portions of the specifications and claims.

The products ofthe invention are largely attained by careful selection of the yarns utilized in weaving the bandages of the invention, particularly the warp yarns, and in their method of treatment during and after weaving. It is preferred that the bandages of the invention be woven on needle looms of various types, a preferred loom being the Libby Loom as illustrated and described in United States Patent No. 2,584,891 issued to C. F. Libby on February 5, 1952, but other needle looms are suitable for producing the bandages of the invention, as are ordinary shuttle or other narrow fabric looms. Certain embodiments of the invention may be produced on wide fabric looms with the fabric then slit warpwise after application of elastic sealing material to make the cut edges ravel-resistant.

The warp yarns of the products ofthe invention must be extensible in the finished bandage so that those yarns which are non-elastomeric in nature must be made extensible by spinning or by distortion as so-called stretch yarns. Yarns which are made extensible by treatment after being woven are particularly suitable. In general it is preferred that there be two yarns in every pick although suitable bandages may be made from single pick construction.

The preferred construction utilizes elastomeric warp yarns which constitute about 1/3 to 1/4 of the total number of warp yarns. When the bandage is to have woven or knitted selvages, it is preferred that the edge warp yarns be elastomeric. When the bandage is slit from wider fabric, however, there is little advantage in the construction wherein edge warp yarns are elastomeric. Corespun elastomeric warp yarns are preferred to wrapped yarns, and yarns with synthetic rubber cores are preferred over rubber core yarns. Spandex core yarns with 40 to denier cores are entirely suitable. In general, with 120 denier cores the elastomeric warp yarns may be fewer and more widely spaced than with 40 denier yarns. It is to be understood, however, that the modulus of elastomeric yarns in the same core size varies considerably, and while yarns of smaller diameter are preferred it is possible to use a larger diameter yarn of low modulus without departing from the invention. The size of the elastomeric core is not, therefore, critical. Rather the stretch range and the compression decay of the completed bandage is the important consideration. It is preferred that the spacing of the elastomeric warp yarns across the fabric be fairly regular but the bandage is functional where the spacing is from every third yarn to every fifth yarn disregarding the elastomeric edge yarn on selvage edge bandages.

Those warp yarns which are intermediate the elastomeric yarns may be spun yarns and stretch yarns. Where a considerable degree of absorption is desired, spun rayon yarns may be utilized exclusively but it is preferred to use a mixture of resilient synthetic stretch warp yarns such as nylon superloft yarns with the spun absorbent warp yarns on about a 1:2 ratio. We find that 70/2 nylon superloft yarn is excellent for this purpose. For the absorbent warp yarns we prefer 20/1 spun rayon yarns.

The yarn utilized largely determines the weight of the bandage in the relaxed condition. The weight per square inch should be in the range of.1 to .15 grams to provide the desired flexibiltiy, ease of application and lack of bulk as well as making possible a bandage which will provide a high degree of ventilation. Thus if the bandage is outside this weight range, lighter or heavier yarns should be utilized to bring the bandage within the proper weight range. The filling yarn can be utilized to adjust the weight most easily, especially if the fill yarn is doubled. We prefer spun rayon 20/1 yarns in the filling. Rayon yarns are preferred to cotton yarns because cotton yarns although satisfactory need considerable pretreatment to make them absorbent and reduce the shrinkage and are not as soft as spun rayon yarns.

The bandages of this invention are woven with about 16 to 24 picks per inch. Where doubled yarns are used this provides 32 to 48 ends of filling yarn per inch. Where the filling yarn is not introduced by a needle loom, a two-ply single filling is preferred.

The warp yarns are under the usual tension while the bandage fabric is being woven. Subsequently and preferably immediately thereafter, the bandage is subjected to a suitable heat treatment which may be provided by infrared lamp, hot air, or by other well-known heat sources, including steam, which may be wet or dry, preferably the latter. The bandage components should be heated to within the range of 200t0 240F. This can be done most expeditiously as the fabric is drawn from the loom and while the fabric is looped or otherwise arranged to permit relaxation and retraction of the elastomeric and stretch yarns in the fabric. A fabric woven with 20 picks per inch before such treatment should have about 40 to 60 picks per inch in the relaxed state after this heat treatment. The fabric can then be wrapped into rolls of varying lengths with or without finishing the cut ends.

When the bandages of the invention have the locked knitted selvages of the preferred embodiments such as the bandage illustrated in FIGURE l, ravelling is at a minimum and even when several picks are cut at the ends of the bandage, loose threads normally do not occur. When ordinary woven selvages form the side edges, such as in the bandages illustrated in FIGURE 7 or when the side edges are cut edges which occur when wide fabric is slit into narrow bandages of the invention, some loose threads may occur. Normally this is not a serious shortcoming even when the bandage is used in an emergency to cover an open wound directly without the usual wound dressing. The inner cut end may be doubled back at a point removed from the wound so as to interpose a thickness of bandage between the cut end and the skin. The bandage may i then be reversed to cover the end so that the latter is sandwiched between bandage layers and effectively sealed from the wound. When the bandage is used over a conventional wound dressing or directly over a sprained joint or other traumata where the skin is not ruptured, ravelling at the bandage ends is of little importance. It is to be understood, however, that although the preferred bandages of this invention have cut edges, the ravel resistance of the bandage ends may be increased by any of the known techniques without departing from the invention.

The bandages of this invention should stretch to lengths at least 2.2 times the lengths of their unstretched relaxed lengths (120 percent stretch) when subjected to longitudinal stretching forces in the range of about .4 to about .6 pound per inch width. Bandages which have materially less than the above elongation invariably are wrapped at dead stretch, which means that the force of wrapping may be quite high with the result that a tourniquet effect may be created. If, on the other hand, the force applied is too little, the compressive force exerted by the bandage when wrapped is insufficient up to the point of dead stretch to prevent excessive swelling. When the force necessary to stretch the bandage to the requisite degree is significantly above .6 pound per inch width, it is possible to achieve optimum bandage compressive force in the wrapped area but it is no longer likely that the proper compressive force can be achieved by a person untrained in bandaging.

Bandages which have the requisite elongation when stretched by an elongating force in the designated range may be made from a fairly wide range of elastomeric cores which have different cross-sectional areas and moduli of elasticities. There are two rather apparent means of modifying the stretch characteristics of the bandages of the invention. Such modification may be brought about by varying the number of elastomeric warp yarns across the width of the bandage or by varying the cross-sectional area of the elastomeric core used, or both. Obviously, if the core material and the number of cores across the bandage width are the same, reduction of the core cross-sectional area will lessen the necessary stretching force, and vice versa. Obviously, also if the core material and cross-section area are constant, the necessary force will vary with the number of cores across the bandage width. Within narrower bounds one may vary the force necessary for the requisite elongation of the bandages of the invention by selection of cores of the same cross-sectional areas but with varying moduli. The moduli ofcores falling within the broad definition of spandex, for instance, vary somewhat from manufacturer to manufacturer.

While being in the stretched condition for some time all compressive bandages have a decay of compressive force. The bandages of this invention are no exception, but this decay when occurring in the proper amount is a definite advantage since as swelling of traumata occur the compression is relieved, thus preventing painful constriction necessitating rewrapping of the bandage. The preferred bandages of this invention have a construction which causes the compressive decay to increase to a maximum and then to remain constant. When measured as hereinafter explained, the preferred embodiments of the invention have a maximum decay of compressive force at the end of an hour greater than 1/4 but not materially greater than 2/5 of the original force of application per inch of bandage width. The bandages of this application have utility when the decay of compressive force is outside the preferred range, however.

When the embodiment of the invention is one woven on a wide loom, warpwise narrow bands of leno weave may be incorporated at points across the fabric where the fabric is to be slit. The fabric is thereafter slit within the leno bands to provide narrow bandages of the invention having ravel resistant side edges. Otherwise warpwise bands across the fabric may be coated or impregnated with a sealing material which will cause the out side edges after slitting to be ravel resistant but will not materially inhibit lengthwise stretching of the bandage. Preferably the sealing material is a thin film of thermoplastic material which has a low modulus ofelasticity but if the material is interrupted either upon application or upon stretching, it may be relatively thicker and need not be elastic. Suitable materials are polyurethanes, vinyl copolymers and polyacrylates.

One or both surfaces of the bandages of the invention may be made tacky by overall application of pressure sensitive adhesive. Likewise, one or both surfaces of the bandages of the invention may be coated with a cohesive but not tacky material, such as polyvinyl acetate.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 illustrates a preferred bandage fabric 10 of the invention which is preferably woven with warp yarns which do not need to be slashed and which include elastomeric yarns. In the example illustrated in FIGURE 1 the elastomeric yarns 1] occur as the outermost warp yarns and as every fourth warp yarn, but the percentage of elastomeric warp yarns is largely dependent upon the size and characteristics of the core of the elastic yarns. In general, such elastomeric yarns constitute about 1/3 to 1/4 of the total number of warp yarns disregarding the extra elastic yarn which occurs when both edge yarns are elastic. Synthetic rubber core covered yarns are preferred and corespun yarn is preferred to wrapped yarn. Other preferred warp yarns which are utilized in conjunction with the elastic warp yarns are stretch yarns such as crimped nylon superloft 70/2 yarns with 13 filaments and 8 turns per inch, and rayon yarns, particularly 30/1 rayon yarns. These yarns may be used together. The fabric 10 of FIGURE 1 is shown with every other warp yarn 12 of rayon, the intermediate warp yarns being alternately nylon yarns I3 and elastomeric yarns 11. The particular rayon yarn preferred is a 30/1 spun rayon. The fabric is shown as it is being woven on a Libby narrow web loom with knitting needles 16 and 17 producing knitted locked selvages. The fabric is woven by the method illustrated in United States Patent No. 2,584,891 to C. F. Libby, issued February 5, 1952. As is shown, the weft yarns l4 and 15 are introduced as doubled yarns in alternation from large yarn packages at each side by the in and out motion of the weft fingers l8 and 19, the needles taking a loop of each weft yarn and drawing these through a previously taken pair of weft yarn loops and casting offa stitch. Thus in FIGURE 1 the needle 17 when it retracts will pull loops of yarn 14 and 15 through the previously formed loops 20. On the other edge, the needle 16 has just cast off the loops 22 and the new loops 21 are in the hook of the needle.

FIGURE 2 is a graph showing typical characteristics of the bandage fabrics of this invention. In the particular embodiment whose characteristics are illustrated, the upper curve 25 marked T=0 was obtained by measuring the force in pounds per inch width of portions of bandage stretched respectively 20, 40, 60, 80, and percent beyond the relaxed length and drawing the curve. Each bandage portion was held at its respective stretch for one hour. The decay curve 26 marked T 1 hr." was prepared by measuring the retractive force exerted by the bandage after one hour while maintaining the same respective amount of stretch for each of the respective portions and drawing the curve. Other typical dressings of this invention may require from about .4 pound to about .6 pound per inch width to obtain an initial stretch of 120 percent.

FIGURE 3 illustrates another typical bandage fabric 30 of the invention with elastic warp yarns 31, rayon warp yarns 33, and crimped nylon warp yarns 32. The rayon weft yarn 34 is introduced by the needle 37 as a doubled yarn from a large yarn package on the right. A natural selvage 38 is produced on the right edge while a knitted selvage 39 is produced on the left edge of the needle which draws the end loop of the doubled weft yarn through the previous end loop of weft yarn.

FIGURE 4 illustrates another typical bandage 40 of the invention. This embodiment may be produced on the shuttleless loom mechanism illustrated in United States Patent No. 2,095,480 to C. F. Schlegel, issued October 12, 1937, wherein a rayon or other weft yarn is introduced from the right side from a large package by a curved weft finger, is looped around another yarn 44 and withdraws, laying a second weft yarn in the shed. The yarn 44 becomes an edge warp yarn but is drawn from a large package on the left. The yarn 44 is an elastic yarn in the illustrated embodiment, as are warp yarns 41. Warp yarns 42 are preferably rayon yarns, while warp yarns 43 are preferably crimped nylon yarns. This fabric illustrates that the warp yarns need not always have the elastic yarns equally spaced although that is the preferred construction.

FIGURE 5 illustrates another typical fabric of the invention made on a loom of the type illustrated in United States Patent No. 2,789,583 to C. Devaud, issued April 23, 1957. The operation of this loom is fully explained in the patent but, in brief, the needle 59 carries a doubled weft of yarn 58 through the shed of elastic warp yarns 51, spun rayon warp yarns 52 and crimped nylon warp yarns 53, whereupon the looped end of the doubled weft yarn is caught by the hook 60 which rotates and pulls the doubled weft yarn in such a manner as to cause the cop 61 to pass relatively through the loop thus introducing the locking yarn 54 which is preferably similar to yarn 58. The loops 55 and 56 of locking yarn 54 are pulled alternately over and under the edge warp 51 as the doubled weft is drawn back into the shed somewhat by the withdrawal ofthe needle 59.

FIGURE 6 illustrates a treated portion 65 of fabric 66 of the invention, to which is applied a resinous material 67 in discrete spots or as an interrupted coating. Preferably the spots are applied in emulsion form or from solvent solutions by spraying. Any resinous material which has a high coefficient of friction, such as a rubbery material or latex or a resin which has inherent tackiness or which has been rendered soft or tacky by mixture, such as a rubber-resin blend, makes an excellent non-slip product.

FIGURE 7 illustrates another typical fabric 70 which is made on an ordinary narrow fabric loom. In this embodiment, the elastic yarns 71 occur every fourth warp yarn, as do the nylon crimped yarns 73, the two yarns alternating with the remaining warp yarns 72 which are of spun rayon. The filler yarns 74 are also of spunrayon.

Preferred examples of this invention have covered elastomeric warp yarns but satisfactory bandages of the invention may be made with bare elastomeric yarns.

Likewise, bandages which have some absorbency are preferred but bandages of the invention which are made wholly with non-absorbent yarns are satisfactory for some purposes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred bandages of the invention are those of the type illustrated in FIGURE l with cut ends. The side edges are knitted as illustrated. Such bandages may be made in various widths, usually ranging from 2 to 6 inches. It is preferred that the filling yarns be 20/1 spun rayon. The warp yarns are preferably of three different types, and the number of warps preferably is a number divisible by four plus one additional elastomeric warp yarn. The outermost warp yarns and every fourth yarn across the bandage is preferably a corespun yarn with the core 70 denier spandex with a spun covering of 30/1 rayon. Intermediate between each elastomeric warp yarn is a nylon 70/2 superloft warp yarn and separating the nylon and elastomeric warp yarns are 30/1 spun rayon warp yarns. These latter spun rayon warp yarns constitute one half and the nylon warp yarns constitute one fourth of the total warp yarns,

ignoring the extra outermost elastomeric warp yarn. The preferred bandage is woven with the usual warp tension and with 20 picks per inch or 40 filling ends per inch, but after subjecting the bandage to dry steam while relaxed the bandage shrunk so that in the relaxed state it has about 60 picks per inch. The resulting bandage may be stretched percent to a length 2.2 times its relaxed unstretched length by a force of .5 pound per inch width. After one hour at 120 percent stretch, the loss in retractive force was about .2 pound per inch width.

We claim:

1. A woven, ribbon-like, compression bandage having ravelresistant side edges and weighing in the range of about .10 to about .15 gram per square inch when relaxed, incorporating elastomeric warp yarns, crimped synthetic warp yarns and spun warp yarns, the elastomeric warp yarns constituting from about 1/3 to about 1/4 of the total warp yarns, said bandage being capable of extension to a length of at least 2.2 times its unstretched relaxed length by an initial force applied lengthwise in the range of about .4 to about .6 pound per inch width the retractive force of said bandage while being in stretched condition for one hour gradually decaying from the initial force to relieve the compressive force exerted by said bandage when used as a wrapping.

2. The bandage of Claim 1 wherein the elastomeric warp yarns are corespun yarns with synthetic rubber cores, wherein the crimped synthetic warp yarns are nylon superloft yarns and wherein the spun yarns are rayon spun yarns.

3. The bandage of Claim 1 wherein the ravel-resistant edges are woven selvage edges.

4. The bandage of Claim 1 wherein at least one of the ravelresistant edges is a knitted edge.

5. The bandage of Claim 1 wherein the side edges are cut edges made ravel-resistant by the application of a sealing material to said edges.

6. The bandage of Claim 1 wherein the filling yarn is a spun yarn.

7. The bandage of Claim 1 wherein the filling yarns are absorbent yarns.

8. The bandage of Claim 1 wherein the filling yarns are spun rayon yarns.

9. The bandage of Claim 1 wherein the retractive force of said bandage after being stretched for a period of time gradually decays from the initial force, the remaining retractive force after the bandage has been stretched one hour ranging from about 3/5 to about 3/4 of said initial force.

10. The bandage of Claim 1 wherein the bandage has applied thereto. on at least one surface thereof. a substantially non-tacky but cohesive resinous material.

11. The bandage of Claim 1 wherein the bandage has applied thereto a tacky material. 

